Distance-measuring instrument.



C. VONHOFE. DISTANCE MEASURING INSTRUMENT. APPLICATION 'FILED NOV-29. I9I3.

LEQKQQ Patented July 27, 1915.

of the instrument.

CHRISTIAN VON HOFE, OF ZEHLENDORF, NEAR BERLIN. GERMANY, ASSIGNOR T0 THE FIRM OF OPTISCHE ANSTALT C. P.-GOERZ AKTIENGESELLSCHAFT, OF FRIEDENAU,

NEAR. BERLIN, GERMANY.

DISTANCE-MEASURING INSTRUMENT.

Specification of Letters Patent.

Patented 2?, 1315.

To all whom it may concern:

Be it known that I, CHRISTIAN voN Horn, citizen of the German Empire, and resident of Zehl'endorf, near Berlin, Germany. have invented certain 'new and useful Improvements in Distance-Measuring Instruments, of which the following is a specification.

The'invention relates to a base line dis tance meter having in the image field a dividing line which is sharp in the whole of its length and formed by the limiting edge of a reflecting coating in the ocular prism device. The invention consists in a construction of a base line telemeter of this kind where the ocular axis is disposed inclined to the plane of the measuring triangle.

A further object of the invention consists in constructing such a base line telemeter with inclined direction of vision in such a manner that the images in the field of View can be reversed at will. The principal efi'ect of such construction consists therein that the instrument can be used either for the observation of top points of distant objects or for the observation of bottom points so that either top points or bottom'points of the objects contact with each other in the dividing line.

The invention is illustrated on the accompanying drawing.

. Figure 1 is a longitudinal section through an embodiment of the invention showing a. part of the optical elements merely diagrammatically. Fig. 2 is across section through the ocular axis.

The telemeter is provided at the ends of its basis with penta prisms 1, 2. The objectives are designated 3, Land the image combining devices or'cross prisms which are as usually arranged in frontof the ocular prism proper are designated 5, 6. The prism 5 isformed as a roof edged prism whereas the prjsmfi is a simple three sided rectangular prism. The ocular lenses are designated 7 and are arranged'in a manner that. their aXis is inclined with regard to the plane of the; measuring triangle.

8 is an adjustable wedge shaped member and 9 a scale plate showing the position of the Wedge shaped member 8'which is characteristic for the distance of the object aimed...

at, the images of which contact with each other in the dividing line ofthe imagefield ng a handle and the like.

perceives in the upper part ofthe image 10 is the rotatable mounting for the crossed or knob 11. rotating mounting 10 with prisms 5. 6 the same can be displaced within the casing of the instrument in such a manner that prism 6 coiiperates' with objective 3 instead". of objective 4 and p-rism 5 with objective 4 instead of objective 3.

12 is the inclined ocular casing containing the ocular the two prisms 13, let contacting with each other and having a reflecting layer 15 provided in the contact surface. The limiting edge 16 of said reflecting lay r 15 is arranged parallelly to the plane of the measuring triangle and positioned in the image plane of theocular so that it appears sharp throughout its length in the image field.

17 is the reflecting surface of prism 14..

18 is the entrance surface of the com-' vertically to the axis of rotation of the prism mounting 10.

The position of the crossed prisms 5, 6 shown on the drawing is preferably used if it is intended to determine the distance of objects waiving in-th'e .air such' as air ships In this instance the observer field an upright image of the distant object, whereas in the lower part of the image field he perceives an inverted image so that he can easily bring to coincidence by shifting the wedge shaped body 8 the bottom points of the distant objects. 1

If it is intended to use the instrument f0 measuring the distance of objects on the earth such as church towers and the like which usually have their most characteristic parts at the top side then the mounting 10 with prisms 5, G is turned for 180 by rotating handle 11 so that the positions of prisms 5, 6 are changed. Then the inverted images appear in the upper part of the image fieldand the upright images in the lower part. The observer therefore can bring-to coincidence the imagesofthe upper points Iofthe distant objects and can there- .fore easily adjustthe instrument on obprisms or image combining device 5, 6 hav-- prism proper consisting of plane; the compound ocular prism further provided with an entrance surface for the Frays, with one reflecting surface substaniially parallel to said reflecting layer in the prism contact surface and with an exit surface substantially perpendicular to the rays reflected thereagainst' by said reflecting layer and reflecting-prism surface.

2. In a base line telemeter a reversible image'combining device, a compound ocular prism immovably mounted in the casing of the insrument, and-"provided with a revfiecting layer in a contact surface of its elements inclined to the plane of the measuring triangle of the telemeter and having a limiting edge substantially parallel to the plane of the measuring triangle and coinciding with an ocular image plane, the compound ocular prism further provided with an entrance surface for the rays, with one reflecting surface substantially parallel to said reflecting layer in the prism contact surface and with an exit surface substantially perpendicular to the rays reflected thereagainst by said reflecting layer and refleeting prism surface. v

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

CHRISTIAN VON HOFE. Witnesses: VVO-IJDEMAR 'HAUPT, HENRY HAsPER.

Copies of this patent may he obtained for five cents each, by addressing the Commissioner of Patents.

Washington, D. G. i 

